Monitoring of chronic wasting disease (CWD) (IV)

The European Commission requested an analysis of the Chronic Wasting Disease (CWD) monitoring programme in Norway, Sweden, Finland, Iceland, Estonia, Latvia, Lithuania and Poland (9 January 2017-28 February 2022). Thirteen cases were detected in reindeer, 15 in moose and 3 in red deer. They showed two phenotypes, distinguished by the presence or absence of detectable disease-associated normal cellular prion protein (PrP) in lymphoreticular tissues. CWD was detected for the first time in Finland, Sweden and in other areas of Norway. In countries where the disease was not detected, the evidence was insufficient to rule out its presence altogether. Where cases were detected, the prevalence was below 1%. The data also suggest that the high-risk target groups for surveillance should be revised, and 'road kill' removed. Data show that, in addition to differences in age and sex, there are differences in the prion protein gene (PRNP) genotypes between positive and negative wild reindeer. A stepwise framework has been proposed with expanded minimum background surveillance to be implemented in European countries with relevant cervid species. Additional surveillance may include ad hoc surveys for four different objectives, specific to countries with/without cases, focusing on parallel testing of obex and lymph nodes from adult cervids in high-risk target groups, sustained over time, using sampling units and a data-driven design prevalence. Criteria for assessing the probability of CWD presence have been outlined, based on the definition of the geographical area, an annual assessment of risk of introduction, sustained minimum background surveillance, training and engagement of stakeholders and a surveillance programme based on data-driven parameters. All positive cases should be genotyped. Sample sizes for negative samples have been proposed to detect and estimate the frequency of PRNP polymorphisms. Double-strand sequencing of the entire PRNP open reading frame should be undertaken for all selected samples, with data collated in a centralised collection system at EU level.

Research on Selected Wildlife Infections in the Circumpolar Arctic-A Bibliometric Review

One Health, a multidisciplinary approach to public health, which integrates human, animal, and environmental studies, is prudent for circumpolar Arctic health research. The objective of our bibliometric review was to identify and compare research in select infectious diseases in Arctic wildlife species with importance to human health indexed in English language databases (PubMed, Scopus) and the Russian database eLibrary.ru. Included articles (in English and Russian languages) needed to meet the following criteria: (1) data comes from the Arctic, (2) articles report original research or surveillance reports, (3) articles were published between 1990 and 2018, and (4) research relates to naturally occurring infections. Of the included articles (total n = 352), most were from Russia (n = 131, 37%), Norway (n = 58, 16%), Canada (n = 39, 11%), and Alaska (n = 39, 11%). Frequently reported infectious agents among selected mammals were Trichinella spp. (n = 39), Brucella spp. (n = 25), rabies virus (n = 11), Echinococcus spp. (n = 10), and Francisella tularensis (n = 9). There were 25 articles on anthrax in eLibrary.ru, while there were none in the other two databases. We identified future directions where opportunities for further research, collaboration, systematic reviews, or monitoring programs are possible and needed.

Chronic wasting disease in Norway-A survey of prion protein gene variation among cervids

Susceptibility of cervids to Chronic Wasting Disease (CWD), a prion disease, can be modulated by variations in the prion protein gene (PRNP), encoding the cellular prion protein (PrP^C ). In prion diseases, PrP^C is conformationally converted to pathogenic conformers (PrP^Sc ), aggregates of which comprise infectious prions. CWD has recently been observed in its contagious form in Norwegian reindeer (Rangifer tarandus) and in novel, potentially sporadic forms, here called 'atypical CWD', in moose (Alces alces) and red deer (Cervus elaphus). To estimate relative susceptibility of different Norwegian cervid species to CWD, their non-synonymous PRNP variants were analyzed. In reindeer, seven PRNP alleles were observed and in red deer and moose two alleles were present, whereas roe deer (Capreolus capreolus) PRNP was monomorphic. One 'archetypal' PRNP allele associated with susceptibility was common to all four cervid species. The distribution of PRNP alleles differed between wild and semi-domesticated reindeer, with alleles associated with a high susceptibility occurring, on average, above 55% in wild reindeer and below 20% in semi-domesticated reindeer. This difference may reflect the diverse origins of the populations and/or selection processes during domestication and breeding. Overall, PRNP genetic data indicate considerable susceptibility to CWD among Norwegian cervids and suggest that PRNP homozygosity may be a risk factor for the atypical CWD observed in moose. The CWD isolates found in the Norwegian cervid species differ from those previously found in Canada and USA. Our study provides an overview of the PRNP genetics in populations exposed to these emerging strains that will provide a basis for understanding these strains' dynamics in relation to PRNP variability.